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Machines Like Us

Why Tononi should allow that conscious entities can have conscious parts

Thursday, 07 June 2012
by Eric Schwitzgebel

On March 23, I argued that eminent theorist of consciousness Giulio Tononi should embrace the view that the United States is conscious—that is, literally possessed of a stream of phenomenal, subjective experience of its own, above and beyond the experiences of all its citizens and residents considered individually. My argument drew on Tononi's work from 2004 through 2009 arguing that any system in which information is integrated—that is, virtually any causal system at all!—is conscious. Tononi's one caveat in those works is that to count as a "system" in the relevant sense, an informational network must not be merely a subsystem within a more tightly integrated larger system. I argued that since the U.S. is a system in Tononi's sense, either it or some more tightly integrated larger system (the whole Earth?) must be conscious by Tononi's lights. While in other posts I had to do some work to show how I thought Daniel Dennett's, Fred Dretske's, and Nicholas Humphrey's views implied group consciousness, Tononi seemed an easy case.

However, my March interpretation of Tononi was out of date. More recently, (here [in note 9] and here [HT Scott Bakker and Luis Favela]), Tononi has endorsed what I will call an anti-nesting principle: A conscious entity cannot contain another conscious entity as a part. Tononi suggests that whenever one information-integrated system is nested in another, consciousness will exist only in the system with this highest degree of informational integration.

Tononi defends this principle by appeal to Occam's razor, with intuitive support from the apparent absurdity of supposing that a third group consciousness could emerge from two people talking. But it’s unclear why Tononi should put much weight on the intuitive resistance to group consciousness, given his near panpsychism. He thinks photodiodes and OR-gates have a little bit of conscious experience; so why not some such low-level consciousness from the group too? And Occam’s razor is a tricky implement: Although admitting the existence of unnecessary entities seems like a bad idea, what is an “entity” and what is “unnecessary” is often unclear, especially in part-whole cases. Is a hydrogen atom an unnecessary entity once one admits the proton and electron into one’s ontology? What makes it necessary, or not, to admit the existence of consciousness in the first place? It is obscure why the necessity of admitting consciousness in a large system should turn on whether it is also necessary to admit conscious experience in some of its subparts. (Consider my Betelgeusian beeheads, for example.) Tononi’s anti-nesting principle compromises the elegance of his earlier view.

Tononi's anti-nesting principle has some odd consequences. For example, it implies that if an ultra-tiny conscious organism were somehow to become incorporated into your brain, you would suddenly be rendered nonconscious, despite the fact that all your behavior, including self-reports of consciousness, might remain the same. (See Ned Block's "Troubles with Functionalism.") It also seems to imply that if there were a large enough election, with enough different ballot measures, the resulting informational integration would cause the voters, who can be conceptualized as nodes or node-complexes in a larger informational system, to lose consciousness. Perhaps we are already on the verge of this in California? Also, since “greater than” is a yes-or-no property rather than a matter of degree, there ought on Tononi’s view to be an exact point at which higher-level integration causes our human-level consciousness suddenly to vanish. Don’t add that one more vote!

Tononi's anti-nesting principle seems only to swap one set of counterintuitive implications for another, in the process abandoning general, broadly appealing materialist principles—the sort of principles that suggest that beings broadly similar in their behavior, self-reports, functional sophistication, and evolutionary history should not differ radically with respect to the presence or absence of consciousness.